Are you sure it's seated properly and the AGP slot is free from crud?
It's definately a hardware problem, nothing to do with drivers or anything like that - but I've seen several cards do that when not securely in the slot.
Don't throw it out, get a friend to try it in his PC for you to make sure of it's condition - but even if it's broken in half it's still worth keeping hold of - things like monitor connectors and GFX card fans don't sprout from the ground, you might need the spare parts one day. Also, if your considering overclocking your next card, then a spare fan on the memory chips can help.
Van-B
Put those fiery biscuits away!